Foil applying device



ug- 3, 1937- c. MILLER 2,089,033

' l FOIL APPLYING DEVICE Filed Jan. 16, 1937 2 Sheets-Sheet'l "-Lf QTY f i, l 21 INVENTOR.

ATTORNEY.

ug. 3, 1937. A 7. MILLER FOIL APPLYING DEVICE Filed Jan. 16, 1957 2 Sheets-Sheet 2 Patented Aug. 3, 1937 UNITED STATES PATENT oFFicE 15 Claims.

This invention relates to the manufacture of dentures in which the articial teeth are mounted in a plate formed of a molded plastic. Certain resinoids, such as the now widely used Luxene, have proven to be especially suitable when properly handled, and the best dentures'being made today are formed of'this type of substance. In the preparation of dentures from these materials, it has been found that the plastic mold in which the denture is formed must be lined with some impervious material, such as tin foil. which is chemically inert towards the resinoid. Unless such a lining is used, the moisture in the plaster causes the resinoid to become whiteand opaque instead of being a life-like translucent pink.

It has hitherto been the practice to apply the tinfoil to the mold by hand and to laboriously smooth it down and fit it into the surface irregularities. One of the principal objects of this in- 20 vention is to provide a method of and apparatus for fitting the tinfoil to the mold quickly and accurately.

Another object of the present invention is to provide an apparatus by means of which tinfoil can be .applied to the. mold by a person having less skill and patience than is now generally required.

In order to explain the invention, reference is made to the drawings, in which Fig. 1 is a sectional view through one of the preferred forms of the invention as it appears in carrying out a step of one process for which it is adapted.

Fig. 2 is an elevation of a rubber guard member forming a part of the apparatus shown in Fig. 1.

Fig. 3 is a sectional view through the form of the invention shown in Fig. 1 as it appears in carrying out a step of a second process for which it is adapted.

Fig. 4 is a sectional View of .a modified form of part of the apparatus shown in Fig. l.v n

Fig. 5 is a plan View of a waxed up-case invested in the lower half of a flask before the Vtinfoil is applied.

Fig. 6 is a sectional view on the line 6--6 of Fig. 5 looking in the direction ofthe arrows, but taken after the tinfoil has been applied. o Fig. 7 is a plan view of the waxed-up-case and lower half of the flask shown in Fig. 5 after the teeth and wax have been removed. l

Fig. 8 is a sectional view on the line 8-18gof Fig. '7 looking in the direction of the arrows, but taken after the tinfoil has been applied.

Fig. 9 is a sectional view of the assembled flask after the wax has been removed.

Fig. 10 is a sectional View of a modified form of the invention.

In the preparation of dentures, an artificial stone model Il having the shape of the gums and other mouth parts which the denture is to t is prepared. On this model il, the denture is formed in wax I2, and the teeth I3 are set into the wax I2 in their proper positions, forming what is called the Waxedup case. The waxed-up case II, I2, I3 is then invested in thelower half I4 of a flask by means of plaster l5, as shown in Figures 5 and 6, and it is covered with tinfoil I6. The tinfoii le is applied in a. plurality of pieces so that it will be able to iit the surface of the waxed-up case without being stretched excessively at any point. The lower half I4 of the flask and the waxed-up case II, I2, I3 covered with tinfoil I6 are then placed in the apparatus shown in Fig. 1.

This apparatus forces the tinfoil I6 to t tightly against the surfaces of the teeth I3, the wax I2, the model Il where it extends beyond the wax I 2, and the plaster I5. It consists of a circular base I'I with an upstanding rim lla within which the end of a cylindrical shell I8 fits. A guard ring I9 covers the edge of the iiask Il and the space between the ask Ill and the shell I8. The guard ring i9 is provided with .a pair of depending lugs I9@ which engage grooves Ilia. in the ask and center it under the opening in the guard ring I9.

A hollow rubber ball is placed on top of the guard ring I9 and the ilask Ill and its contents. The space within the ball 2li is full of water ZI or other liquid, but the amount of water 2l is preferably not enough to fill the ball out to a spherical shape. In practice, I nd that the best results are obtained by rst completely filling they ball 2@ with liquid ZI, making certain that all air is expelled and then expelling about one third of the water, although this amount may vary within wide limits. 4

The ball 26 is partially covered'by a heavy rub- 4 ber guard 22 in the form of a hemispherical shell with awlarge deeply serrated hole inthe top. The ball 20l and guard 22 are covered by a piston 23 which can slide in the cylinder or shell I8. The r underside of the piston Z3 is hollowed to receive the guard 22 and ball 20, and the top is provided with circular strengthening ribs 23a.

The apparatus assembled as described above is then placed in a press and the piston 23 forced r towards the base Il. The pressure set up in the liquid 2! within the ball 20 causes its lower part to press tightly against the wax model I2, the teeth i3 and the plaster I5. The tinfoil I6, which lies under the ball 20, is thus pressed against the wax model I2 and the teeth I3 with considerable pressure. In practice, with a force of several thousand pounds exerted by the press, the pressure on the tinoil I6 may be as much as three hundred pounds per square inch. This pressure ensures that the lower surface of the tinfoil I5 assumes the exact shape of the surface of the wax model I2 and the teeth I3.

The lower half I4 of the ilask with the tinfoiled waxed-up case comprising the model II, the wax l2, the teeth I3 and the tinfold I6 are then removed from the tinfoiling apparatus and the upper half 24 of the flask is invested. This consists of lling it with plaster 25 so that the tinfoiled waxed up case II, l2, I3 and I3 is secured in the upper half 24 of the ilask as well as in the lower half I4. The wax I2 is then melted out leaving a cavity 26 (as shown in Fig. 9) the exact shape of the desired denture. The tinfoil l5 and teeth I3 are left imbedded in and adhering to the plaster 25 in the upper half 24 of the flask.

The ask I l and 24 is then opened, any wax I2 remaining in the cavity 26 is removed, and the model II is covered with tinfoil 21 which is pressed down tightly by the apparatus shown in Fig. l. This second application of tinfoil is carried out exactly like the rst application except that the tinfoil 21 is applied directly to the model II after the wax I2 and teeth I3 have been removed from it, while the tinfoil I54 was applied to the entire waxed-up case comprising the model II, the wax I 2 and the teeth I3. The result of 'the first and second tinfoiling operations are shown in Figs. 6 and 8 respectively.

Since the tinfoil I applied in the first operation was transferred to the upper half 24 of the flask as described above, the surfaces of the cavity 2S carried by both halves I4 and 24 of the flask are now coated with tinfoil IS and 21, and the mold thus prepared is ready for the molding of the denture.

One or two details not mentioned above contribute to the durability of the device and the ease with which it is handled. The lugs I3a. on the guard ring I9 are tapered to facilitate placing it on the flask I4, and the edge I9b of the aperture in the ring I9 is beveled or rounded to avoid cutting the ball 20. The rubber guard 22 is normally larger in diameter than the inside of the cylinder or shell I8 so that it ts tightly enough to hold both litself and the piston 23 above it in place when the apparatus is disassembled. Thus the shell I8, guard 22, and piston 23 can be conveniently picked up and placed in position together.

The apparatus described above can also be used as shown in Fig. 3 for carrying out a new and improved process producing better results.

In this process, the impression 30 of the patients gums is made of some rigid material such as the thermo-plastic compositions similar to sealing wax commonly used for this purpose. The impression 30 carried by aconventional impression tray 3| is setin a material such as plaster 32 in such a way that the portion of the surface of the impression 30 which corresponds to the contact surface of the future denture is exposed but the rest of the mass is smooth. This can be done in a tray similar to the lower half I4 of a flask or in a tray adapted to just flt within the shell I8, making the use of the guard ring I9 unnecessary, or it can be done as shown directly on the base I1. In any case, the exposed surface of the impression 30 is covered with tinfoil 33 and the tinioil 33 is pressed down tight by means of the apparatus I8, 20, 2I, 22 and 23 as shown in Fig. 3.

An articial stone model similar to the model II shown in Figures l, 6, 7, 8, 9 and 10 is then cast in the conventional manner on the tinfoiled impression 3G. When the impression 30 is carefully broken away from the model, the tinfoil 33 remains on the model. The model is then waxed up, and the teeth placed, forming the waxed-up case which differs from those made prior to the introduction of this process and from the waxed-up case II, I2 and I3 described above in that there is a layer of tinfoii 33 between the model and the wax. The waxed-up case is then invested in the lower half of a ask, and it is coated with a second layer of tinfoil on the other side of the wax. The tinfoiled case in then invested in the upper half of a ilask and the wax melted out, leaving the second layer of tinfoil and the teeth adhering to the plaster in the upper half of the flask and the rst layer 33 adhering to the plaster in the lower half. The investing of the` case in the lower and upper halves of the flask, the application of the second layer of tinfoil, and the removal of the wax are similar to those operations as carried out with the waxed-up case II, I2 and I3 shown in Figs. 1, 5, 6 and 9, but in this improved process a layer of tinfoil 33 is already Il DOSlOn against the model corresponding to the model I I. Therefore, after the wax is removed, both upper and lower surfaces of the molding cavity have tinfoil on them.

The advantage of the improved process described immediately above is that the'layer of tinfoil 33 is applied to a positive impression instead of to a negative one. In the conventional process, the tinfoil is applied to the model, which is a negative, and the thickness of the tinfoil is subtracted from the space in which the denture is molded. Thus the denture is inaccurate by the thickness of the tinfoil. In my process, on the other hand, the tinfoil is applied to a positive, the impression 30, whose place is filled rst by the wax and then by the molding material forming the denture. The tinfoil is thus on the outside of the space in which the denture is molded and does not subtract from it. Moreover, any wrinkles that may be formed in the tinfoil are away from the denture forming space instead of in it.

Modifications of a' part of the apparatus described above are shown, in Figs. 4 and 10; In Fig. 4 is shown a modiedbase 5U to replace the base I1 and guard ring i9 shown in Fig. 1. The modified base is intended for use with asks having a sloping parting line and is made with a recess 5I shaped to hold the bottom of such a flask with its parting surface level. The walls of the recess 5I are provided with projecting portions 50a which fit into and iill grooves provided in the sides of the bottom of the flask for the reception of lugs on the top of the flask.

Another modified form of base 52 is shown in Fig. 10. 'I'he base 52 is in the form of a shallow cylindrical cup tting within the shell I8 and having a low circumferential flange 52a upon which the shell I8 rests. This View also shows how the rubber ball 20 fits tightly against the waxed up case l I, I2 and I3 when pressure is applied to the piston 23.

What I claim is:

1. An apparatus for pressing a sheet of flexible material onto a portion of the surface of an irregularly shaped object comprising a cylinder adapted to enclose the object, filler means adapted to be placed around the object to close any passage that may exist in said cylinder around said object, a piston slidable in said cylinder, a ilexible-walled hollow member lled with liquid and adapted to be placed between said object and said piston, and a iiexible guard adapted to encircle said hollow member and to extend from said filler means to vsaid piston and to lie partly between said hollow member and said piston.

2. An apparatus as described in claim 1 in which said flexible guard is formed of thicker material than said enclosed member.

3. An apparatus as described in claim 1 in which the face of said piston is concave.

4. An apparatus as described in claim 1 in which the edge of said piston in contact with said cylinder is sharper than ninety degrees.

5. An apparatus as described in claim 1 in which said flexible guard has an aperture in the portion between said hollow member and said piston.

6. An apparatus as described in claim 1 in which said flexible guard has a serrated aperture in the portion between said hollow member and said piston.

'7. An apparatus as described in claim 1 in which said flexible guard ts in said cylinder tightly enough to support its own weight and that of said piston.

8. An apparatus as described in claim 1 and provided with a removable base upon which said object and said cylinder may rest.

9. An apparatus for pressing a sheet of flexible material onto the exposed surface of an irregularly shaped object invested in a flask comprising a cylinder adapted to encircle said flask, a guard ring adapted to fit in said cylinder and on the rim of said flask, said guard ring serving to close off the space between said flask and said cylinder, a piston slidable in said cylinder, a hollow member having flexible walls and filled with liquid and adapted to iill the space between said ask and guard ring and said piston, and a iiexible guard adapted to encircle said hollow member and to extend from said guard ring to said piston and to lie partly between said hollow member and said piston.

10. An apparatus as described in claim 9 in which said guard ring is provided with means for locating said ask with respect thereto.

ll. An apparatus as described in claim 9 in which said guard ring is provided with lugs adapted to engage the sides of said flask.

12. VAn apparatus as described in claim 9 in which said guard ring is provided with lugs adapted to t into grooves in the sides of said ask.

13. An apparatus as described in claim 9 and including a base adapted to receive and support said flask and said cylinder.

14. An apparatus as described in claim 9 in which the inner edge of said guard ring is rounded.

15. An apparatus for pressing a sheet of ilexible material onto the exposed surfaces of an irregularly shaped object invested in a ask having an oblique parting line, said apparatus comprising a base adapted to hold said flask with the l parting line level, a cylinder adapted to t around said base, means adapted to ll the space between the sides of said flask and the walls of said cylinder, a piston slidable in said cylinder, a hollow member having flexible walls and lled with liquid and adapted to ll the space between said flask and means and said piston, and a flexible guard adapted to encircle said hollow member and to extend from said means to said piston and to lie partly between said hollow member and said piston.

CHRIS MILLER. 

